Bald eagle in flight in Alaska (Avalon/Universal Images Group/Getty)

The Trump Administration is weakening the Endangered Species Act, which has assisted the recovery of more than 50 species since it became law in 1973.

The Act has saved the bald eagle, California condor, grizzly bear, and northern gray wolf from possible extinction, and reintroduced grey wolves to Yellowstone National Park in 1995. Other recovered species include humpback whales, gray whales, Louisiana black bears, three types of kangaroo, American alligators, and several plants.

More than 1,600 plant and animal species are protected, and 99% of those on the endangered list have not gone extinct.

But on Monday the US Fish and Wildlife Service and the National Oceanic and Atmospheric Administration announced changes to the Act, such as consideration of economic factors before categorizing a species as endangered or threatened. Animals listed as “threatened” will no longer receive the same protection as those in the “endangered” category.

The Administration is also defining risks to species on a case-by-case basis, relaxing the definition of risk in the “foreseeable future”.

The Administration claims that alterations will ease regulatory burden, but they will also open up more protected land to development drilling for resources — complementing other steps to reduce the area of national parks.

Interior Secretary David Bernhardt insisted the changes bring the protections “into the 21st century”: “An effectively administered act ensures more resources can go where they will do the most good: on-the-ground conservation.”

But Leah Gerber, professor of conservation science at Arizona State University, explains to TIME magazine:

The new rules completely undermine the strength of the ESA. The point of the act is to prevent extinction, this is going to do the opposite. It’s going to undermine efforts to recover species….

The worry that the act is ineffective or needs revision I think needs to be considered in the context of, yes, it could be more effective, but weakening it will not make it more effective.

The rules will take effect in September, but California and Massachusetts Attorney Generals say they will sue to prevent changes, and other states are expected to follow.

Senator Tom Udall of New Mexico, the top Democrat on the committee overseeing the Interior Department, said Democrats are considering invocation of the 1996 Congressional Review Act, which can invalidate rules established by federal agencies.

Meanwhile, Donald Trump and senior officials have withdrawn environmental regulations and standards, suppressing Government studies of climate change and even barring mention of it on agency websites.

This summer, the UN and International Union for Conservation of Nature published separate reports on climate change and human activity threatening up to 1 million species with extinction.